Hydrogenated resins



10 products may be prepared by subjecting, for expoints stated herein refer to those obtained by 25 merization. -For example, the dimer of 1,4-dihyyellow to amber, depending on the degree of 25 50 -and,rwhile stillhot, is suspended one inch below drogenation, I am able to produce colorless resin- 50 Patented SephZO, 1938 I UNITED'STATES- PATENT OFFICE HYDROGENATED 'RESINS Harold S. Holt, Wilmington, Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. pplication November 24,1937,

' Serial No. 176,231

13 Claims. (c1. 260- -2)' This invention relates to the manufactured the mercury. The temperature of the mercury resinous materials and more particularly to the at a point near the end of thewire at the instant preparation of artificial resins, both liquid and] the cube appears at the surface, is multiplied by solid, which are resistant to deterioration by the the arbitrary factor of 1.25 and 2 is added to 5 action of light and heat.- the product to give the apparent melting point U.- S. Patent No. 2,055,708 describes the prepain degrees centigrade. For example, if the merration and properties of certaln resinous macury temperature is 100 C. when the cube -apterials which may be made from dihydronaphpears on the surface, the apparent melting point thaleneand homologues thereof. These resinous will be (100 1.25) +2", or 127 C. The melting ample;1,2-dihydronaphthalene, 1,4-dihydronaphthis method. By using as starting material difthalene or a mixture thereof of the action of a ferent isomers or mixtures and by producing solution of the alkali metal addition compound of mixtures containing the different polymers, resinnaphthalene or other polycyclic aromatic hydroous materials may be obtained from dihydrol5 carbon, 'asdescribed in the above mentioned naphthalene or its homologues, having different 15 patent. The resinous productis recovered by' apparent melting points or difierent degrees of distillingofi solvent and unpolymerized material. hardnessor viscosity at room temperature.

These resinous materials described in Patent The above described'resinous polymersof the No. 2,055,708 are polymers of the hydrocarbons dihydronaphthelenes and their polymers, whenfrom which they are made; for example, those freshly prepared and free from impurities, are 20 made from dihydronaphthalene are polymers of" clear, transparent and colorless. The solid forms 1,2-dihydronaphthalene or 1,4-dihydronaphtha-- have the appearance of colorless, crystal glass, lene or mixtures of these. The polymers are liqexcept for a slight fluorescence. When impure, uid orsolid, depending on the degree of polythey may have a coloration varying from light dronaphthalene is a viscous liquid at room temimpurity H w these materials are more perature, while the tetramer is aybrittle solid. or less subject to actinic efiects and usually be- These resinous materials,.like resins in general, come colored or have their color deepened on do not have the definite, sharp melting points' exposure to heat and light, especially ultraviolet '30 characteristic of crystalline compounds, but grad lig t. In a number of uses fo wh h Such resins ually' change from the solid state to viscous liquid are well adapted, this lack of stability to light when suitably heated, the viscosity of the melt is a distinct disadvantageslowly decreasing as the temperature is raised. An object of the present inventionis to provide The'term melting point" or .apparent melting means for stabilizing the above described resin- 1 point, as used herein with reference to these ous polymers of dihydronaphthalene and their 5 .resinous materials, and also to the products of omolo s st ac action- A further the present invention hereinafter described, refer object is to prepare substantially transparent,

. to the temperature at which apparent liquefaccolorless or light colored resinous materials which 'tion commences. Such apparent melting point is are stable to light and heat. My invention also 40 determined by a standardized procedure known comprises the novel resinous products obtained 0 as the cube melting point method, which is by my process hereinafter described. Further generally applicable to various resinous subobjects will be apparent from the following destances. In this method a /2 inchcube of the scription. i t in m on th e dof a, bra The above objects are attained in accordance wire 0.1 inch in diameter. The wire is bent at with the-prese v n n y hy n in h 45 rightangles one inch from the end on which above des ri e in s p y r of dihydrothe cube is cast, the end of the wireextending naphthalene and its homologues. I have found through the center of the cube. When the cast that the resulting hydrogenated products are cube has solidified, it is removed from the mold very stable to light. By a proper degree of hythe'surface of a body of mercury which has been ous materialswhich show no trace of color after heated to 6( )-to .90" C., the main portion or the exposure to ultraviolet light of high intensity for suspending wire being in'avertical position. The many hours, whereas the parent material be mercury is then heated at the r'ateof 3 C. per comes highly colored by exposure to the sam 56 minuteuntil the cube appears at the surface of light in a relatively short time. '55

Although the dihydron'aphthalene polymers are resinous in character, I have found that they can be hydrogenated readily unden suitable conditions. A method which I have found particularly effective consists in dissolving the polymer in a hydrocarbon solvent, ,e. g. decalin (decahydronaphthalene), an ether solvent, e. g. dimethyl ether of ethylene glycol or other suitable solvent and applying hydrogen under pressure at 200 to 300 C. in the presence of a hydrogenation catalyst, e. g., finely divided nickel. Attemperatures below 200 C., the polymers absorb hydrogen relatively slowly. A preferred temperature range for rapid hydrogenation is 240 to 275 C. However,fhydrogenation at temperatures below 200 C. may be carriedout effectively if the reaction is continued for a sufficient length of time. Hy-

drogen pressures of 1000 to 2000 pounds per square inch have been'found to be suitable for effective and rapid hydrogenation. The various known hydrogenation catalysts may be used, for example, finely divided nickel. Acatalyst concentration of, for example, '7 to 35 grams per liter of the polymer solution is satisfactory. If

desired, the polymers may be hydrogenated without the use of a solvent, by operating at temperatures at which they are in the liquid state. However, because of the viscous nature of the polymers, I prefer to hydrogenate them in solution, especially the polymers of higher molecular weight. Various modifications of the above described hydrog'enating. process will be apparent to those skilled in hydrogenation of organic compounds.

The hydrogenated products made by the present. invention may contain three or more moles of added hydrogen (Hz) for each mole of dihydronaphthalene (C10H10) originally present. Thus, where a polymer having the empirical formula: (CmHw) 1; is hydrogenated, the'product willper mole of CmHm have been absorbed. ,The hy-.

drogenated product is generally colorless and,

when sufficiently hydrogenated, is very stable to" 'light and heat. It has been found thatthe unhydrogenated polymers which are colored as produced or which have become colored or darkened by the action of heat or light are greatly improved irr appearance by my hydrogenation process. Thus, a colored resin may be changed to a colorless or only very lightly colored, light-stable prodnot by the hydrogenation. Because of this fact,

'my process is of value for reclaiming 'colored,.

unsalable material. It has been found that light-stable resin by myprocess, it is necessary to carry the hydrogenation to a relatively high degree. Thus, the introduction of 1-2 moles of hydrogen per mole of ClOHlO generally does not appreciably increase the stability towards actinic action. Usually, it is necessary to introduce at -least 2.5 to 3 moles of hydrogen per 'mole of 0101110, the minimum amount depending on the particular sample. When this minimum point is reached, the hydrogenated product is very stable towards-light. I prefer to hydrogenate the material until it will absorb no more hydrogen,which corresponds-to the introduction, in general, of 3 duced per mole of CIOHIO.

in order to obtain a.

violet light test.

. organic solvents.

to 3.25 moles of hydrogen per mole of C1oI-I1o in the resin.

0n the other hand, the decolorizing effect described above often may be obtained by a very light hydrogenation, e. g. the introduction of 0.5v

to 1 mole of hydrogen per mole of CinHm. The increase in heat stability varie's directly with the degree of hydrogenation, the heat stability gradually increasing as the amount of hydrogen introduced is increased.

It has further been found that the hydrogenation increases the melting points of the polymers and the increase in melting point varies directly with. the amount of hydrogen introduced. This result was surprising and unexpected, since hydrogenation of cyclic organic compounds regularly lowers the melting point. For example, naphthalene is a solid, melting at 80 C., while its hydrogenation products, dihydronaphthalene, tetrahydronaphthalene and decahydronaphthalene are ,all liquids at 20 C. In general, the melting point ,of the polymer will be increased by my process about 14 C. for each mole of hydrogen intro- Thus my method enables the preparation of resins of different melting points, as desired, over a wide range; The hydrogenated resins made by my process may range from viscous liquids to solid materials having apparent melting points up to about 200 C. A particularly useful group of products which may thus be prepared are those having apparent melting points of 100 to 200 C. .These are brittle, glass-like materials which may be utilized in a variety of resin compositions for imparting hardness to the'mass.

The hydrogenated products of the present invention exhibit excellent stability toward both light andheat. For example, a clear, transparent, colorless, glass-like resin was made by hydrogenating the tetramer of 1,4-dihydronaphthalene until hydrogen absorption was substantially complete, the amount of hydrogen absorbed being equivalent to about 3 moles of hydrogen per mole of CioHm. This' resin, after exposure outdoors in an unshaded location for a period of 18 months was substantially unchanged and developed no color. Samples of the unhydrogenated polymer developed a yellow color. This hydrogenated polymer of 1,4-dihydronaphthalene lamp (manufactured by the General Electric unhydro'genated polymer developed a yellow color naphthalene homologue'is intended to include dihydronaphthalene itself, as the first member of-the homologous'series. The other homologues include the.various alkyl derivatives ofdihydronaphthalene, e. g. methyl dihydronaphthalene, ethyl dihydronaphthalene, dimethyl dihvdronaphthalene and so on, which may be polymer-' ized to resinous materials according to the method of the above mentioned U. S. patent.

'Iclaim:

1. The process comprising hydrogenating a resinous polymer of dihydronaphthalene.

2. The process comprising hydrogenating a resinous polymer of 1,4-dihydronaphthalene.

3. The process comprising hydrogenating a resinous polymer of 1,2-dihydronaphthalene.

4. The process. comprising reacting a solid,

resinous polymer of. dihydronaphthalene with resinous polymer of 1,4-dihydronaphthalene with hydrogen.

6. The process comprising reactinga resinous 'polymer. of dihydronaphthalene homologue with hydrogen.

7. The process comprising reacting a resinous polymer of dihydronaphthalene homologue with hydrogen until at least 2.5 moles of hydrogen per mole of 'CmHm have been absorbed.

8. The process comprising reacting a solid, resinous polymer of dihydronaphthalene with hydrogen until 2.5 to 3.25 moles of hydrogen per mole of C10H1o have been absorbed.

9. A hydrogenated, resinous polymer of a dihydronaphthalene homologue.

l0. A light stable, colorless, hydrogenated, resinous polymer of dihydronaphthalene.

11. A light stable, colorless, hydrogenated, resinous polymer of 1,4-dihydronaphthalene.

12. -A colorless, transparent, hydrogenated, resinous polymer of dihydronaphthalene which is stable to ultraviolet light radiation.

13. A solid, colorless, transparent, hydrogenated, resinous polymer of 1,4-dihydronaphthalene which remains substantially colorless after being exposed for four hours to ultraviolet light radiated .from a quartz mercury vapor arc lamp.

mom) s. HOLT. 

